Mechanical clearance regulator



May 7, 1940. o. M. BURKHARDT MECHANICAL CLEARANCE REGULATOR Filed April13, 1935 I :s Sheets-Sheet 1 EMF/ ATTORNEYS I May 7, 1940.

O. M. BURKHARDT MECHANICAL CLEARANCE REGULATOR Filed April 13. 1933Fig.5

s Sheets-Shet 2 INVENTOFZ ATTORN EVE? o. M. BURKHARDT 7 2, 0,152

MECHANICAL CLEARANCE REGULATOR Filed April 13, 1933 3 Sheets-Sheet 5ATTORNEYS til Patented May 7, 1940 our r E srAr as ear-Em r orrics2,200,152 MECHANICAL CLEARANCE REGULATOR Otto M. Burkhardt, Cleveland,Ohio,- assignor to Thompson Products, Inc.,. Cleveland, Ohio.

ApplicationApril-IS; 1933, Serial No.- 666338 15 Claims. (Cl. 123-90)mechanisms, for every complete cycle of the justment to insure adefinite clearance between the'va-lve'and its actuating member, theconventional cam. This clearance is necessary in*co-n---- ventionalmechanisms to allow'for'expansion of the linkage between this cam andthe valve, otherwise thevalves would-not properly close the combustionchamber, resulting in inefficient combustion;

. Because of improperseating of'thevalveor the entirelack of seating dueto lack of clearance'in the linkage .of the mechanism; the valveis'deprived ofa most essential coo-ling period which normally occursduring its contact with the Water-cooled seat in the combustion chamber.This aggravates the heating of the valve and causes further expansionand; consequently, worse seating; The valves will then start-to warp,burn, crack and break. This is often followed by serious damage to theengine.

If the clearance between the valve andits actuating-members increases,either due to normal wear of the cooperating members, or due to adifierential in expansionof these members and their supports, then thevalve mechanism becomes objectionabl-y noisy and the impact forces aregreatly increased, causing pounding'of valve seats, excessive Wear,surge, and breakage.

strictly speaking, a warm-up period follows every: increase in throttleopening. because: the heatvincrea'ses directlywith thepower' output.

Cooling-01f periods occur every time the throttle opening is decreased;These'difierentialsin'exgpansion and' contraction change theclearance.andwith it the-valve timing. This'is detrimental to the properfunctioningof the engine;

It is further well known to automotive engineers that within thevalvemechanism there exists" considerable'surge. In general, this surge isnoticeable athigher engine speeds but more particularly is it noticeableat certain speeds known'as resonance speeds. This surge interferes withthe desired true kinematic relation between the valve and itsactuating'member; the cam;

This surge is-thecause of the valve bouncing 01f its seat when it isexpected to close andremain closed. Bouncing of the valve causes Veryhigh uncontrolled closing velocities and consequently high impacts. Thelatter'are the cause. of pounding away of valve seats, excessive noise,excessive wear, and failures. Bouncing of the valve further' causes adelay in closing of the valve which results 'inlossof power;

Various devices forautomatically adjusting clearances inthe linkagesystem of valve mechanisms have been previously developed. The presentinvention overcomes many diificulties. encounteredin' the constructionand operation of such devices. An arrangement operative on a principlesimilar in some respects to that of J the present invention is shown,described. and claimed inmy Patent Serial No. 1,943,063, February"20,1934.

Several preferred forms of mechanism by which I accomplish the-objectsabove set forth are illustrated in the accompanying'drawings asappliedto an L hea'd'engine'and' also an'overhead valve type engine.'Iheabovestated. objectsand my device for eliminating the-difficultiesoutlined will become more apparent'in'the following. description whichrelates tothese drawings, in which Fig. l is a fragmentary crosssectionof an engine block of the L-head type, showing an adaptation'of myinvention to a-valve mechanism;

Fig. 2 is a similar fragmentary viewshowing the position-of the partsduring. a; subsequent operation;

Fig. 3-is airagmentary elevation taken'along the lines 3-3. of Fig. 1;

Fig. a'is. a simplified.forcediagram illustrating. the. forces presentduring certain operating- 'conditions';

Fig. 5 is a fragmentary plan view taken along the lines 5--5 of Fig. 1;

Fig. 6 is a fragmentary vertical section similar to Fig. 1, showing amodified adaptation of the regulating cam mechanism;

Fig. 7 is a fragmentary horizontal section taken on a plane indicated bythe line l--'I of Fig. 6;

Fig. 8 is a vertical fragmentary section showing an adaptation of myinvention to the rocker arm arrangement of an overhead valve type ofengine; and

Fig. 9 is a fragmentary sectional plan taken on an offset planeindicated by the line 99 of Fig. 8.

' In the arrangement of my invention as illustrated in Figs. 1, 2, and3, there is shown a valve Ill having the usual stem i2on which isdisposed the usual valve closing spring l4 positioned as shown between astationary guide collar any adjustment, is slidably positioned in aguide provided in the motor casing 22. This guide is also greatlysimplified because the lifter is a plain cylinder not requiring theenlarged head of conventional lifters. The lifters upper end is incontact with the lower end of the valve stem l2 as indicated at 24. Thelower end of this lifter element 20 is shown as resting against the fiatside of a spherical element 26 mounted in a coacting socket 28 in thevalve-actuating lever 30.

The end 32 of the lever 36 which is nearest the valve center line isbifurcated, and within it is suitably mounted a roller 34 which duringthe valve opening period is vigorously urged downwardly into contactwith the surface of the cam 36 by pressure from the valve spring l4.When the valve is closed, the downward pressure of the valve spring I4is reacted by the stationary valve seat 15 and its effect onroller 34ceases.

. In the form shown, the end 38 of lever 30 is also bifurcated to carryby means of a pin 42 a regulating spiral or wedge-shaped cam member 40.For the design under consideration two nonrotating but slidable blocks46 are further mounted on pin 42. These blocks are located to the rightand left of the cylindrical end portion designated 38 of the lever 30and they rest against coacting surfaces 41 provided on the motor casing.The cam 40, having fiat sides, also mounted on pin 42, is held inposition by a slot provided in end 38 of lever 30. The cam is free toperform a-limited angular motion about the axis of pin e2. In order tocontinuously urge the thick part of the wedge-shaped cam 40 betweensuitable cooperating surfaces so as to take up excess clearance, aspring 44 is employed. This spring, in the case of Figs. 1, 2, 3, hasboth ends anchored to the non-rotating but slidable blocks 46. Themiddle portion of this spring acts on the wedge-shaped cam. as shown at48. The spring preferably consists of a number of turns and is normallyunder tension urging the thick part of cam 44] between cooperatingsurfaces. One of these cooperating surfaces is a flexible member 50which under normal pressure yields a very small amount,

Theoretically, the support 50 need not necessarily be of flexible metalbut cam 40 may operate efficiently by engagement with an ordinarysupport for bearing engagement therewith. Flexibility within "he body ofmetal may be all that is required. However, the flexible support 50 willbe found to produce better results and to act more efiiciently and istherefore deemed advisable for accomplishment of the best results. I

The outer surface of cam 40 is so shaped that a pressure'exerted on thisouter surface will not pass through the center of the hole in the camwhich coincides with the center line of pin 42 but will give rise to aforce couple. This force couple is smaller than the sliding frictionbetween the cooperating surfaces, that is, between the contact surfacesof cam $0 and support 5%! and between cam 46 and pin 42. This featuremakes cam Myself-locking against the action of this force couple andhence against all static pressure acting on cam lt. If, however, support50 yields,

a relative motion musttake place between the contact surfaces. Thefriction force between cam 49 and support 50 is opposed to sliding ofthe surfaces relative to each other and therefore it induces cam Ml toroll relative to support 59 anamount corresponding with the amount ofdeflection of support 59. It will be obvious from the design thattheforce couple above mentioned as well as the relative motion between thecontact ing surfaces combine to induce cam 40 to roll toward the thinpart or clockwise on pin 42. This lowers end 33- of lever 30 and with itto a smaller extent valve l0 relative tocam lobe 31. Because of this thevalve opens a few thousandths of an inch less than it would open if end38 of lever 30 were not lowered. The outer surface of cam 4i} may followthe laws of a logarithmic or an arithmetic spiral, or it may follow aninvolute or someother desirable curve.

To open the valve, only vertical pressure is required. When cam 36 isrotated to urge through its lobe 31 the roller 3t upward, the actuatingforce willbe normal to the surface of cam'lobe 3'! and will pass throughthe center of roller 34. The direction of this force varies, hence provision has been made through the proper locating of support 5% andslidable blockstt which bear against surfaces of the motor'casing, toconstrain end 38 of lever 30 from all motion except that required foropening the valve and for regulating I the clearance, namely to followthe yield of support 50.

A very simple form of clearance regulating device is obtained bycorrectly shaping lever arm. 30 r.

and by locating the roller 34 at end 32, and the clearance regulatingparts at end 38 of lever 30 in efiicient relation to cam 36. In the formshown in Figs. 1, 2, and 3, the lever 30 and the various clearanceregulating parts mounted on it are so located that the forces betweencam lobe 31 and roller 34 during the entire valve opening period actpreponderately upward and with a bias to the so that any force actingnormally upon it through cam 46 will be opposed in a manner that lever30 can not be displaced to the left. There is another reason forinclining support 50 which will be apparent from the following Thelocation for lever 39' and the parts mounted upon, it are chosen so thatduring the valve-openeingiperiod a suitable: part: ofithesva'lve spring.pres-- sure plusuthe: inertia; of-r theereciprocatingparts."

acts downwardly on endi,3.8:ot'lever-30;.. Adowm ward pressure; willproduceia slight Ldefleetion of the supporta5.0:;and-consequently;blocks 463will; slide a small amount downwamil;'r.elati-ve..-to.,thev

surface. 41.. Due to;.the-.; inclinationzoi J the. support 5|]: relativeto theesurface; 413; andsduee-to the, frictional; adherence'of.camAflztdthe.support..z5ll,..

:2anddue to. a. forceicouplewhic h ls the-:resultoithe. prevailing:pressurev and-,the; characteristics;

chosen for the: contour. of cam A0,". thiscamz. 405

will, according to. principles; previously. stated;-

turn; (clockwise. in.-.F.'ig. ,1) about .the; axisof pin i 42; anamount. which. is,-.in... direct relation; to the small. amount .of,deflection :of support Strand cons sequently; of 1 the; downwardmovement of end: 3.8

of the;lever.;30-.;. Thisdownwardmoyement isrcontrolled by, correctlyproportioning; the following.

:3First, the magnitude of the downwardipressure transferredthrough-lever .30 from; the, point. of

application. ofthe; main force; the'pressure, of-

valvespring l4zplus the-inertia vofthe reciprocate ing parts .to .endz38of lever 30. Second. the yield sof...the.flexible; support 50,: Third,the contour: of

cam-.140: whichrollsa definite amount againstsupport 50- towarda'smaller radius o-r..toward the thin part of; its wedge-like-shapeduring the slight,

downward motion.

As stated, when the; valve closes, all pressure ceases; mechanisrnthevalve opened, for example, .001" to-.005 lessthan itwouldopen were itactuated through; a conventional, mechanism. Therefore,

:lstthe. valve will also. closeloefore. roller 34 hasarrived:atatheuconcentric:or. base-circle, 35: of cam 35 Astherollerapproaches'thebasecircle after the closing, of: thevalve, a.clearance of several,

thousandths ofzaninch will tend to1developwithinathe'valveeactuatinglinkage. While' this clearance tends =.todevelop,r.the;.potential;energy stored in: the slightly deflected;support fiiltisr released.

Its nature is to'return to the no-load positionand bysmdoing-itiorcesthe end 38 of the lever. upwardly by that .amountwhich: it yielded dueto the flexibility of the 'suppOrtEflQ. Whenthisis completed,v the end3.8 tofzlever: filly-still hasto .move

upward iby thatsmall. amount whichzthe camiwa.

provided, due: to its. partialsrotation. aboutpin 5.0;, 42..It'isimportantito note-that when theflexible sup-port 50. returnsto..its unstressed. or no-loadr position, cam 4fls.doesxnot' returntotherangular position which it occupied; when the. downward. The reasonfor. thiSf. is; as.

movementistarted; appointed out before that during...the downwardmovementtthere is the frictional .-.adhesion .of the pointsin contactaugmented, by. theaction .of a

force-couple causing clo-chwiserotation of the cam 40 to. its thinner orshorter radius aportion. On

(20,; the return tothe no-load position oi-the flexible support, andofthe clearanceregulating parts.

cam Midoes not change its angular position relative to pin 42oecause-the frictional resistance betweenthe contacting surfaceswhichmight roll (Z53 cam 40 back to its original position, isnow op-'posed and overcome by that same force couple which previously helped inslightly rolling'cam lfi'. On the return motion, a rolling-of the camisfurther opposed-by the static frictionbetween cam and pin 42. Due tothese factors; namely the force-couple 'being on downward yield" additive-toand on return to no-load position subtractivefrom thefrictionbetween cam'fi'fl and'sup port' 50, andb'ecausetests-reveal -it' tobeso, itis J an established fact that" on the downwa-rd motion- Because.of the; clearance regulating does not r011 v back to its originalposition. This partial rotation of cam 40 on pin 42 provides a. little;clearance to insure not only proper valve seating but it provides roomfor any expansionor other-change that'mighthave taken place within thelinkage.

Now the thickend of cam Mlisconstantly urged between support 5!): andpin 42, causing endr38' of lever 30 to move further upwardly until allclearance is out of the linkage, namely, when the' valve which isnowheld firmly, to ,itsjseatby' spring M, stops lever, 38 frommoving'further up-' wardly, This completes one adjustment for one.complete turnof the cam shaft which constitutes one complete enginecycle.

The arrangement shown in Figs. 1, 2, and,3:

has the advantage that the clearance regulating parts at the end 38 oflever 34! can be small in each other rather than on top of each other.Also, the sliding blocks 46-:are free to .slide considcam 40 does roll,but on the upward motion it erable distances up' or downwithoutencounter ing structural limitations.

mechanisrnwill readily;compensateiforrthis;

Therefore, nottonly'does the: conventional ad-i justmentbeconreventirely superfluous, butIdue to; the fact: that .the position of the.flexible member I 50 can be lowered or raised relativetO'ilihEfIl'lDliOl casing 22, a very Wide. range of manufacturingvariations and wear changesxcanoccur. before limitations in theclearance regulating range approach inefiiciency or inefi'ectiveness.

The construction shown. inv Eigs. (Stand 7- isuso conceived that apluralityv of l eccentrics 61- are mounted upon a. common shaft whichextends parallel to the axis of thecam-shaft. This shaft is. supportedat intervals bysuitable bracketszz.

Uponthe outside of each eccentric El is mounted.

one wedge-shaped cam 40 with its return-spring- 44. Alongside ofcamAm-with its return spring 44, there is further mounted upon theoutside of eccentric Bl the end-38 m lever -30? These partsembraceandsubstantially cover the outside'of' eccentric 6i and they areadapted to'oscillate on of the spiral spring tends to turn cam 4!? sothat it is. wedged snugly between the fleXibIestopBD-E and the eccentric8i. Theotherend of thespirall fit! tends to wedgethe eccentric 6|betweenendiifia.

spring supplements this, action, in so far. as it of lever 301 and thestationary shaft $2., Asbefore, thespiral cam bears upon a flexiblesupport.- 561 which is secured as indicated.- Thdflexible support is soformed and fastened as to permit of resilient action whenv pressure isapplied thereto through the'medium of end, 33 of lever 30,

eccentric 6i and cam 40. This pressure originates and bears directrelation to forces necessary to open and close the valve.

surface 41. In the arrangement'here'under considera-tion, an analagousdownward motion'ofth'e clearance regulating" parts is-- brought aboutThis permits of very: large changes .in-the. partszof: the valve mecha-'nismto, take. place andf the. clearance; regulatingzj The outerend:of=this-'spiral-spring'is fixed fro In the'description of'Figs.1,12; anol'3', it was. noted that blocks 46- slide downward relative tofdiameter, as the parts are mounted alongside off.

through end 38 of lever 38 being mounted upon eccentric 8| andtransmitting pressure to this eccentric SI and so causing it topartially turn about fixed shaft 82. Due to the eccentric mounting ofthe clearance regulating parts relative to shaft 82, these parts arelowered when pressure occurs during the valve-opening period by anamount corresponding with the yield of support 58. Thus, itwill be seenthat in the arrangement as shown, end 38 of lever 38 together witheccentric 6|, cam lll, return spring M, and support 58, perform duringand immediately following the valve-opening period and under theinfluence of the prevailing pressures, the desired clearance regulation.exactly as described in detail for the arrangement shown in Figs. 1, and3.

The mathematical principles of valve clearance regulation can best begiven by referring to Fig, 4, which is a skeleton of a desirable form ofclearance regulator. The support is shown reversed'in Fig. 4, withrespect to its point of mounting, for the sake of convenience ofillustration.

Cam 38 is rotated in clockwise direction. The pressure FR acting normalon. the cam surface passes through the center line of the roller asshown. Opposed to FF. is the pressure F1. which is the sum of thepressure of valve spring l4 plus the inertia of the reciprocating,parts. It is apparent that:

Fall- 1 1.

We shall first discuss application when F1. is vertical while FR isinclined. The vertical component of FR being fv acts on lever arm Cwhich is larger then 0. Because of this, balance of the systemnecessitates the existence of another vertical component at end 38 oflever 38 which we call f"v. Balance of the system requires thatf'v+f"v=FL FR has a horizontal component fh which is reacted by an equaland opposite force 1"h at end 38 of lever 30.

f'h and ,fh form a force couple of moment .f'nXd The system is subjectedto one clockwise moment FLxc counteracted by 2 counterclockwise momentsf'vC and f'hd FLc=fvC+f'hd The force fv is the vertical component of theforce Fs which is the pressure exerted by end 38 of lever upon support58. The horizontal component of Fe is not necessarily equal to f"h. Thehorizontal component of Fe resists 1"v only incidentally. Adequateresistance for f"v. is obtained in the guide surfaces l1. Un; derpressure Fs support 58 yields. Due to friction, the contact points (8)of the cam and support adhere together. Hence, sum of force couple FsXlplus moment of friction at (0) namely FsXJXR of cam cause rolling of camabout pin 42 toward smaller radius of cam. In the latter expression fdenotes coefficient of friction. R denotes radius of that part of cam 48which momentarily is in contact with support 50.

When force FL disappears due to closing of valve, spring support 50continues for a moment pansion in linkage while the remainder is takenout by spring 44 through cam 48.

In Figure 4,the support 58 is located to counteract such forces asresult when a e. In all cases when a. c the component f"v must'act.downward. Inasmuch as fv is derived from F3 it is evident that in allcases when a c support 50 must be so located relative to'cam that force.

Fs acts downwardly.

Effectiveness and simplicity of the device are assured by properlypositioning the arm '30 in an angular relation with respect to the axi'sof the: valve stem and by locating the ends 32 and 38' of the lever arm38 so that under all operating conditions there are components of forcesacting to hold the clearance regulating members in the desired position.It is also apparent that by suitably varying the angle at which theguide surfaces ill or the supporting member 58 are disposed, thesecomponents may be varied to suit the different conditions that obtain indifferent designs of engines. Itis not'necessary, although here shown,that the center line of the valve intersects that of the cam shaft. Theprinciples apply equally as well when the center line of the valve doesnot intersect that of the cam shaft but passes either to the right orleft of it.

When eccentrics are usedas in the cases illustrated in Figs. 6, 7, 8,and 9, the thick part of the eccentric may also be located to the rightof the axis of the stationary shafts 62 and 83, respectively.

Figs. 8 and 9 represent an'application of the clearance regulator to anoverhead valve engine now to be described in detail.

Mounted in suitable brackets is a stationary shaft 82 which through themedium of eccentrics 83 affords support for the rocker levers 84. Eachrocker lever is provided with an integrally formed collar or hub 85embracing the eccentrics 83 about which the rocker arms turn. The centerof this hub is so located as to obtain the desired relation betweenpushrod and valve motion. Upon the circumference of each eccentricbushing is mounted a cam- 48b. The outside surface of this cam bearsagainst a flexible support 50 which is secured to the top of thebracket. Cam 48 having flat sides 'is free only to perform a limitedangular motion upon the circumference of eccentric 83. In order tocontinuously urge the thick part of the wedge-shaped or spiral cam.

lii between suitable cooperating surfaces so as to take out excessclearance, is aspring 88 which,

like the spring M above described, has one end lll to support flwhich=will yield until its resistance" balances the turning effort.

--cam 540". v

entirely within controlthr'ough properly propor- "velop within the valvelinkage.

Whilesupport-Sfl yields in direction of arrow X, the'eccentric throughcam 40 pushes in direction of arrowY. 'Due'to the frictional adhesion%between the contact surfaces of cam 40 and 'support '50 the cam 40will'tend to' follow supportill indirection of arrow 'X, which causes a"turning of cam Won-eccentric 83. This turning is further helped by-aforce couple which is due to the pressure of the moment onthe contour ofThis motion, as previously stated, is

tioning the cooperating parts. I Y -Identically as in the previouslydescribed ar- 'rangements, when'the valve closes, the cause of allpressure ceases. Due to the yield of support 50 the eccentric 83 hasslightly turned about shaft-82, raising-the center of the hub of'therocker'arm t4 which causes! the valve to close a little sooner than itwould close were it actuated through a conventional roller approachesthe base circle, a clearance of several thousandths of an inch'will tendto de- As soon as pressure diminishes, the potential energy stored up insupport 50 is released. Support Ell will through medium of cam lilcause'eccentric 83 to turn counterclockwise and sourge the hub portionof the rocker arm downward. This eliminates only part of the lost motionbrought about :duringthe opening of the valve; because during the returnto the no-load position of support 50 cam 40 will not turn on eccentric83 because through the'friction between the contacting surfacesof camlll and support 50, the potential energy of this support would now tendto cause came!) to rotate clockwise, which'it can not readily do becausethis would involve entering the thick part of the wedgashaped cambetween the cooperating surfaces; but moreover themoment of a forcecouple due to the design or cam 40 counteracts clockwise motion of cam4% and eccentric-.83. It is only after the effect or the potentialenergy from support50 has been exscope of the appended claims, Itherefore do notwish to be limited to-theparticular designs illustrated.

"In the 'earlypart of this application it'was stated that the inventionwill eliminate surge from'thelinkage "of the valve mechanism. How thisis accomplished will appearfrom the follow It iszwell-known that theentire valve-opening 'period' which lasts aboutone-third of a cam shaftrevolution or about:120- cam shaft angular v motion, usually less than.39" only are available problems the linkage has to be; made light. High1 pressures and light :linkage .cause appreciable mechanism. As theelastic yield within the linkage. The product of the pressure multipliedby this yield represents the energy which is stored up in theValvelinkage. 'Ata car speed of 60 to 70 miles per hour, this storing ofenergy in the valve linkage occurs in less than .003 secondf This timeinterval hap: pens to coincide vnth the frequency of conventional valvesprings. Coincidents of this nature are recognized as prolificsources ofresonance or surge in mechanisms.

More specifically, what happens within the valve linkage is that whenthe geometry of" the cam contour requires a valve velocity of say50inches per second, the valve moves at a' less'er velocity,perhaps'edinches per second, more ortlfi less. At thebeginning of thevalve opening period, the valve always lags behind'the ca'ms angularvelocity bya-n amount corresponding "to the energy stored up within thevalve mechanism 7 due to elastic deformation. 'Hen'ce resonance or surgeis' bound to occur within the valve mechanism. The surge frequency ofthe valve linkage set up by this elastic deformation, remains constantbut the angular velocity of the cam is-subject to wide variations," duetovaria'ticns: in en gine speed and periods in the mechanism is drivingthe cam. shaft.

These facts briefly account for noticeable surge which in the valvelinkage. Ifthere is clearancein the valve linkage, the pressure abovereferred tousually occurs as a shock to the linkage which in turn isknown to aggravate this surge. Now inasmuch as the invention eliminatesall excess clearance, it is obvious that shocks are reduced andconsequently one cause ofsurge'aggravation is eliminated.

"It' is: wellknown that surge 'or'vibr'ations in structural partscanbelessened by the use'of friction devices which tend 'to dampenthemout. One of the advantageous characteristics of my invention is that itis'made'up of a number of parts: which in the performance of theirfunctions move relatively to one another-and so introduce a small amountof friction into the linkage members. This small amount. of frictionhelps further to minimize surgein the entire linkage.

Therefore, With the'invention'I attain not only "clearance regulationbut surge dampening as well ii In an internal combustion engine, thecombination with a valve and a cam shaft, of valveoperating linkageincluding a lever interposed between said valve and cam shaft andadapted to transmit'motio-n therebetween, oscillatable cam meansassociated with one end'of said lever, a

spring normallyforcingthe cam' in one direction,

means permitting movement of the axis of said cammeans, and asubstantially stationary abut ment contacting said cam means, so that.saidca'm means affords a movable fulcrurn'for one end of said leverandacts to move said fulcrum toregulate clearancesand absorb impactsbetween said valve and camshaft.

2. in an internal. combustion engine, the 'combination with a valve and'acam shaft, of valveoperating linkage includinga leverinterposedbetween'said valve and cam shaft and adapted to transmitmotion therebetween, oscillatable cam means associated with one end orsaid lever, a spring normally forcing the cam in one direce tion, andmeans permitting movement of the axis of said cam means so that said cammeans affords a moveable fulcrum for one end of said lever and acts toabsorb impacts and to regulate clearance between said valve and camshaft.

3. In a valve mechanism for an internal combustion engine, thecombination of a valve, a cam shaft, a lever interposedbetween saidvalve and cam shaft, one end of said lever contacting said cam shaft andthe other end of said lever having associated therewith an oscillatablewedge-acting cam member, and means permitting movement of the axis ofsaid cam member, said lever being disposed angularly with respect to themovement of said valve and said cam having means normally forcing thesame in one direction whereby a preponderant force is at all timesexerted in one direction to maintain said lever in an operating positionand said cam afiords a moveable fulcrum to regulate clearness in. thevalve mechanism and to insure constrained movement of said levereffecting opening and closing of the valve.

4. In a valve mechanism for an internal com bustion engine, thecombination with a valve and a cam shaft, of valve-operating linkageincluding a lever angularly interposed between the said cam shaft andvalve, a fixed auxiliary shaft, an eccentric oscillatably disposed onsaid shaft, said lever embracing said eccentric, a wedging camoscillatably disposed on said eccentric, means normally urging said camin one direction, and a reaction element contacting said cam, wherebythe force moments about the center of said aux" iliary shaft would beunbalanced if substantial clearances should exist in the valve mechanismand whereby said cam and eccentric are automatically actuated by suchtendency so as to regulate said clearances.

5. In an internal combustion engine, the com bination with a valve and acam shaft, of a lever interposed between and linking said valve and camshaft and adapted-to transmit motion therebetween, said lever beingactuated at its one end by said cam shaft and said valve being actuatedfrom a point on said lever intermediate its ends, and automaticallyadjustable cam means associated with the other end of said lever andadapted under pressure through said lever to alter the relativeinclination thereof to change the linkage distances between said valveand cam shaft, and adapted when pressure ceases to again change thedistances to insure minimum clearance.

6. In an internal combustion engine, the combination witha valve and acam shaft, of an inclined lever interposed between and linking saidvalve and. cam shaft and adapted to transmit motion therebetween, saidlever being actuated at its one end by said cam shaft and said valvebeing actuated from another point on said lever, and automaticallyadjustable cam means associated with the other end of said lever andadapted underpressure through said lever to alter the relativeinclination thereof to change the linkage distances between said valveand cam shaft, and adapted when pressure ceases to again change thedistances to insureminimum clearance.

7. In an internal combustion engine, the combination of valve-operatinglinkage including a lever arranged between the cam shaft and valve stemand adapted to transmit motion therebetween, a wedge-acting camoscillatably mounted upon the one end of said lever means permittingmovement of the axis of said cam, spring means arrangedbetween said camand lever so as to normally force said'cam towards its larger radius,and a resilient abutment for bearing engagement by said cam, said partsbeing so constructed" and arranged that said cam will be turned aboutits axis towards its smaller radius during the valveopening period andbeing adapted thereby to store energy during said period, and said camturning automatically towards its larger radius during the postvalve-operating period so as to therebyregulate the clearance in themechanism and 'to release such stored energy during saidpostvalveoperating period but only to the extent required.

8. In an internal combustion engine, the combination of valve-operatinglinkage including. a

lever arranged between the cam shaft and valve stem and adapted totransmit motion therebetween, a wedge-acting cam oscillatably mountedupon the one end of said lever, spring means arranged between said camand lever so as to normally force said; cam towards its larger radius,an abutment for bearing engagement by said cam, a slidable mounting forthe end of said lever upon which the cam is mounted and being soarranged as to permit movement of said lever end substantiallytransversely thereof and to wards and from said abutment, whereby saidcam will turn about its axis towards its smaller radius during thevalve-opening period and being adapted thereby to store energy duringsaid period and said cam turning automatically towards its larger radiusduring the post valve-operating period so as to thereby regulate theclearance in the mechanism.

9. In an internal combustion engine, the com-, f

bination of valve-operating linkage including a lever arranged betweenthe cam shaft and valve stem and adapted to transmit motiontherebetween, 2. wedge-acting cam oscillatably mounted a slidablemounting for the end of said lever upon which said cam is mounted, saidmounting com prising a block having slidable engagement with astationary abutment, a resilient abutment for said cam, said resilientabutment extending angularly with respect to said stationary abutment soas to afford a wedging engagement, the lever .end upon which said cam ismounted sliding movement substantially transversely thereof and towardsand from said resilient abutment, said parts being so constructed andarranged that said cam will be turned about its axis towards its smallerradius during the valve-opening period and being adapted thereby tostore energy during said period, and said cam turning automaticallytowards its larger radius during the post valvee operating period so asto thereby regulate the clearance in the mechanism.

10. In a valve mechanism for an internal combustion engine, thecombination with a valve and a cam shaft, of a motion-transmitting leverinterposed between said cam shaft'and valve, a fixed auxiliary shaft, aneccentric oscillatably mounted upon said auxiliary shaft, the one endportion of said lever embracing said eccentric, a wedge-acting camoscillatably disposed on said eccentric, spring means arranged betweensaid eccentric'and can]. so as to normally urge thetwo in oppositeangular directions, and a substantially stationary abutment for saidcam, said parts being so constructed and arranged that said cam will beturned about its axis towards its smaller radius by movement of saideccentric by said lever during the valve-opening period, and

. valve and cam shaft and adapted to transmit [actuated from a pointbetween the ends of said motion therebetween, one end portion of saidlever having operative engagement with said cam shaft for actuation ofsaid lever, said valve being lever, a wedge-acting cam oscillatablymounted upon the other end of said lever, spring means arranged betweensaid cam and lever for normally forcing the cam towards its largerradius, means permitting movement of the axis of said cam and anabutment for said cam, saidparts being so constructed and arranged thatsaid cam will be turned towards its smaller radius during thevalve-opening period and will turn automatically towards its largerradius during the post valveoperating period so as to regulate theclearance in the mechanism. 7

12. In an internal combustion engine, the com bination with a valve anda cam shaft, of an inclined lever interposed between and linking saidvalve and cam shaft and adapted to transmit motion therebetween, one endportion of said lever having operative engagement with said cam shaftfor actuation of said lever, said valve being actuated from a pointbetween the ends of said lever, a wedge-acting cam oscillatably mountedupon the other end of said lever, spring means arranged between said camand. lever for normally forcing the cam towards its large. radius, meansaffording vslidable movement of the end of the lever upon which the camis mounted and in a direction substantially transverselyof said lever,said cam having an abutment extending angularly to the direction of suchslidable movement so as to afford a wedging engagement, said parts beingso constructed and arranged that said cam will be turned towards itssmaller radius during the valve-opening period and will turnautomatically towards its larger radius during the post valve-operatingperiod so as to regulate the clearance in the mechanism.

13. In an internal combustion engine, the combination with a valve and acam shaft, of an inclined lever interposed between and linking saidvalve and cam shaft and adapted to transmit motion therebetween, oneend' portion of said lever having operative engagement with said camshaft for actuation of said lever, said valve being actuated from apoint between the ends of said lever, an eccentric oscillatably mountedupon a fixed shaft, the other end of said lever being oscillatablydisposed about said eccentric, a wedgeacting cam oscillatably mountedupon said eccentric, spring means for normally forcing said cam towardsits larger radius, and a substantially'stationary abutment for said cam,said parts being so constructed and arranged that said cam will beturned towards its smaller radius during the valve-opening period andwill turn automatically towards its larger radius during the postvalveoperating period so as to regulate the clearance in the mechanism.

14. In an internal combustion engine, the combination with a valve and acam shaft, of an inclined lever interposed between and linking saidvalve and cam shaft and adapted to transmit motion therebetween, one endportion of said lever having operative engagement with said cam shaftfor actuation of said lever, said valve being actuated from a pointbetween the ends of said lever,

an eccentric oscillatably mounted upon a fixed shaft. the other end ofsaid lever being oscillatably disposed about said eccentric, and cammeans having oscillatable connection with said eccentric for controllingthe oscillatable movement of said eccentric so as to thereby regulatethe clearance in the mechanism. i

15. In an internal combustion engine, the combination with a valve and acam shaft, of valveoperating linkage including a lever interposedbetween said valve and cam shaft and adapted to transmit motiontherebetween, oscillatable cam means associated with one end of saidlever, a spring normally forcing the cam in one direction, meanspermitting movement of the axis of said cam means, and an abutmentcontacting said cam means, so that said cam means affords a movablefulcrum for one end of said lever and acts to move said fulcrum toregulate clearances and absorb impacts between said valve and cam shaft.

OTI'O M. BURKHARDT.

